Protocol coverage · August 2026

18 protocols, across 9 layers. 5 verifiable maturity levels.

Agentic commerce is standardizing in public and halfway. We publish the real status of each protocol - what we use today, what's in Sandbox, and what we haven't implemented - because integrating on top of a bundled promise is how quarters get lost.

See the matrix Per-platform integrations

Each protocol's status is resolved against the platform's capability registry, not hand-copied onto this page.

Several protocol channels with different levels of connection cross an interoperability layer and end in normalised tools for a single merchant. — ProtocolsProtocols solve different jobs and don't share the same maturity level.The common layer keeps store operation stable: channels in production flow end-to-end; the rest keep visible limits.

Protocol by protocol

What each one solves, and where we stand.

The order reflects usefulness today, not expectation. A protocol with strong backing and an open spec is still a protocol you can't yet use in production.

MCP

Model Context Protocol

Production

AUTHORAnthropic

TRANSPORTStreamable HTTP

SPECmodelcontextprotocol.io

WHAT IT SOLVES

The standard protocol by which an agent discovers tools, invokes them, and reads structured resources. It's the transport: it defines how you talk, not what you buy.

WHERE WE STAND

Transport, tool listing and tool invocation implemented. Every connected store is exposed as a multi-tenant MCP server at POST /{store-slug}/mcp over Streamable HTTP transport, and it is the path all agentic traffic goes through today. What a given store actually serves depends on its own configuration: call `tools/list` and read the answer.

WebMCP

Web Model Context Protocol

Coming Soon

AUTHORGoogle (Chrome) and Microsoft (Edge)

VERSIONW3C Community Group draft

SPECwebmachinelearning.github.io/webmcp

WHAT IT SOLVES

Turns any website into an MCP server: the browser exposes forms, buttons, and storefront data as tools an agent can use. It's what lets checkout close inside the store instead of returning a link.

WHERE WE STAND

The bridge bundle is served publicly. Current tests mock navigator.modelContext; a verifiable run against a browser with native support is still needed before calling it production.

UCP

Universal Commerce Protocol

Production

AUTHORGoogle, Shopify, and a consortium of 30+ companies

VERSION2026-04-08 (Phase B)

SPECucp.dev/latest

WHAT IT SOLVES

The commerce semantics layered on top of the transport: checkout sessions, identity binding, order management, and returns. UCP is to MCP what REST is to HTTP.

WHERE WE STAND

The public capabilities surface responds in production and declares UCP enabled. This confirms deployment, not full coverage of every function in the spec.

x402

Payment over HTTP 402

Sandbox

AUTHOROpen standard

VERSIONOwn binding

SPECOnboarding guide available on request

WHAT IT SOLVES

Reuses the HTTP 402 status code so a server can require payment within the HTTP exchange itself, without sending the agent to a separate flow.

WHERE WE STAND

The rail is deployed and its health is published in production. Availability per scheme and network should be checked before integrating.

A2A

Agent-to-Agent Protocol

Production

AUTHORGoogle

SURFACEAgent Card

STATUSDiscovery deployed

WHAT IT SOLVES

Direct communication between autonomous agents: a buying agent negotiates with a selling agent without going through a human interface.

WHERE WE STAND

The public Agent Card responds in production. This enables agent-to-agent discovery; it doesn't mean autonomous price negotiation is available.

AP2

Agent Payments Protocol 2

Experimental

AUTHORGoogle

ENVIRONMENTDemo

STATUSBridge active in sandbox

WHAT IT SOLVES

Payment mandates with cryptographic verification: the user pre-authorizes the agent to spend up to an amount, with a signature and expiration, and the agent buys within that limit without additional confirmation.

WHERE WE STAND

The bridge is active in the demo environment. It is not presented as a production rail and doesn't replace the authentication and consent requirements that apply to payment.

Protocol-agnostic core

No integration depends on a protocol arriving on time.

The core doesn't know which protocol a request came in through. Rules, limits, and evidence apply the same whether it arrives via MCP, REST, or a binding that doesn't exist yet. That's what lets us have protocols at different stages without blocking anyone: when they advance, they turn on as an extra layer, and what already works keeps working.

DeployedMCP, UCP, and A2A discovery

production

In validationAP2 in demo, x402 deployed but with no merchant settleable, and WebMCP pending a real native browser

sandbox / coming soon

Before integratingCheck surface, flags, network, and commercial scope

check status

Next step

If you're integrating, start with what's in production.

MCP covers discovery, catalog and cart on all five integrated platforms. That is the capability, not the deployment: which merchants are actually connected, and on which platform, is published at /.well-known/merchant-index.json. Everything else layers on top without rebuilding the integration.

Try the MCP gateway See the Agent Rules

18Total protocols

8In production

2Sandbox

9Layers

ProductionSandboxComing Soon

Layer 0 — Structured Web Access

Discovery and data access layer for agent navigation

3 protocols

WebMCPW3C CG Draft (27 Mar 2026)

Coming Soon

W3C Community Group

W3C Community Group standard for agent-to-web interactions via browser APIs

Where we stand: Bridge served, native mode unvalidated: the four bundles are served and their sha256 matches the build, but our E2E suite injects a mocked `navigator.modelContext` and there is no run against a browser with real support.

B2BB2CD2C

DiscoveryW3C Standard

Docs Official site

llms.txt

Production

Jeremy Howard / Answer.AI

Machine-readable format for LLM agent discovery and capabilities

B2BB2CD2C

Discovery

Docs

NLWeb

Coming Soon

Microsoft (R.V. Guha)

Open protocol and tools for building conversational interfaces for any website using Schema.org, MCP and LLMs

Where we stand: Deployed on our side: `POST /{store}/ask` responds and the search pipeline (pgvector retrieval plus re-ranking) is implemented. We cannot claim it indexes or answers — measured 2026-09-03, that route returns VECTOR_DB_UNAVAILABLE because the embedding step is failing upstream, and the `nlweb_ask` tool responds on no MCP surface.

B2CD2C

MCP ToolDiscoverySSE

Docs

Layer 1 — Agent-to-Tool Infrastructure

Core tool integration protocol with standardized JSON-RPC 2.0 interface

1 protocol

Model Context Protocol2025-11-25 (SDK 1.29.0)

Production

Anthropic

Open standard for agent tool integration with standardized JSON-RPC 2.0 interface and tool registration

B2BB2CD2C

MCP ToolDiscovery

Docs

Layer 2 — Agent-to-Agent Coordination

Multi-agent messaging, task orchestration and interoperability

1 protocol

A2A Protocol

Production

Google / Linux Foundation

Open protocol enabling AI agents to discover each other, negotiate communication formats, and coordinate tasks across vendors and platforms

B2BB2C

SSEDiscovery

Docs

Layer 3 — Agent-to-User Interaction

Real-time human-in-the-loop flows with state sync and cryptographic confirmation

2 protocols

AG-UI Protocol

Production

CopilotKit

Open, event-based protocol that standardizes how AI agents connect to user-facing applications with streaming, state patches and tool calls

B2BB2CD2C

SSEDiscovery

Docs

A2-UI Protocolv0.8

Planned

Google

Agent-to-UI: an open Google protocol for agents to describe rich, interactive UI declaratively in JSON, rendered natively by the client. We do not serve it. Our trust component vocabulary is published transport-agnostically at /.well-known/trust-components.json and is served today over MCP Apps

B2BB2CD2C

MCP ToolDiscovery

Docs

Layer 4 — Commerce Discovery & Checkout

Multi-protocol payment initiation and checkout flows for agentic commerce

3 protocols

ACP2026-01-30

Sandbox

OpenAI + Stripe

Open standard for programmatic commerce flows between buyers, AI agents, and businesses with session resume and display context

B2BB2C

MCP ToolDiscovery

Docs

AP20.1 (pre-FIDO donation)

Experimental

Google → FIDO Alliance

Open protocol for secure agent payments via signed Mandates. Donated by Google to FIDO Alliance on 2026-04-28 — currently under review by the Agentic Authentication Technical Working Group, pending external (FIDO) ratification (expected Q3-Q4 2026).

B2C

MCP ToolDiscovery

Docs

UCP2026-04-08 (Phase B)

Production

Google + Shopify et al.

Universal open-source standard for agentic commerce built on REST and JSON-RPC with native A2A, AP2 and MCP support, backed by 20+ global partners

B2BB2C

MCP ToolDiscovery

Docs

Layer 5 — Human-Confirmed Payment Execution

W3C browser-native APIs that bridge agent-initiated checkout and settlement — requires a human present in the browser to confirm payment biometrically or via saved credentials

1 protocol

Payment Request APIW3C CR Draft (27 Jan 2026)

Production

W3C

W3C Candidate Recommendation standard that lets merchants accept Apple Pay, Google Pay and saved cards via a browser-native popup. Generates a Stripe PaymentMethod token — zero PAN data stored, PCI DSS scope reduced. Available as a client capability that complements fully-agentic checkout flows.

B2CD2C

W3C Standard

Docs

Layer 6 — Payments Authentication & Settlement

Tokenization and settlement protocols across fiat, stablecoin, and card networks

5 protocols

x4021.0

Sandbox

Coinbase + Cloudflare

Internet-native payments standard built on HTTP 402 for USDC stablecoin micro-transactions between AI agents and APIs

B2BB2C

MCP ToolDiscovery

Docs

MCAP

Coming Soon

Mastercard

Mastercard agentic tokenization via Stripe pass-through with RFC 9421 Ed25519 HTTP signatures, consent management, and W3C Verifiable Intent receipts

B2BB2C

MCP ToolDiscovery

Docs

VIC

Coming Soon

Visa

Visa Intelligent Commerce with FIDO2 passkeys for tokenized payment flows and recurring subscriptions with trust score boost

B2BB2C

Discovery

Docs

MPPdraft-httpauth-payment-00 (18 Mar 2026)

Planned

Stripe + Tempo Labs

Machine Payment Protocol — payment-method-agnostic M2M payments over HTTP 402 + WWW-Authenticate, with native MCP/JSON-RPC transport. Backwards-compatible superset of x402. Submitted to IETF as draft-httpauth-payment-00. Trusteed positions as the trust+policy layer that MPP and ACP need above MCP.

B2B

MCP ToolDiscovery

Docs Official site

PayPal

Coming Soon

PayPal

PayPal Orders API v2 with agent settlements, subscriptions, invoicing and dispute resolution via @paypal/agent-toolkit

B2C

MCP ToolDiscovery

Docs Official site

Layer 7 — Trust & Identity Verification

Cryptographic identity proofs and passkey-based merchant verification

1 protocol

FIDO2 / WebAuthn

Production

FIDO Alliance + W3C

Passwordless authentication standard with passkeys for merchant identity, 2FA and Digital Credentials API with mDL / SD-JWT-VC support. The endpoint is deployed; adoption or passkey users cannot be claimed.

B2BB2C

DiscoveryW3C Standard

Docs Official site

Layer 8 — Shopper Context & Personalization

Preference sharing and shopper context across agents and retail platforms

1 protocol

SCP

Production

Retail AI Council

Open standard letting shopper preferences, loyalty and behavioral intent travel safely across agents, channels and retail platforms

B2C

MCP ToolDiscovery

Docs

Why multi-protocol?

Agent choice

Agents pick the protocol they support. No negotiation, no fallback errors.

Revenue maximization

Do not lose sales because an agent only speaks x402 and your store only speaks ACP.

Future-proof

New protocols are added via the Plugin Registry. Your integration stays the same.

Single integration

One MCP endpoint, all protocols. The Protocol Router handles detection and routing.

Frequently asked questions

How many protocols can a merchant enable?

All supported protocols simultaneously. MCP, UCP, and SCP are in production; ACP and x402 are in sandbox — the x402 rail is deployed, but no merchant has a settleable configuration, so no payment completes over it today; AP2 is experimental; Visa VIC, Mastercard MCAP, and PayPal are coming soon. The Protocol Router selects the best match based on agent capabilities and merchant priority configuration.

Is there a cost per protocol?

Protocol support is included in all tiers. Settlement fees depend on the protocol provider: Stripe for ACP, which is the rail that actually moves money today. For x402 there is nothing to charge for yet, because no merchant has a settleable configuration and the settle route returns `x402_not_configured`.

Can I add a custom protocol?

Yes. The Plugin Registry supports custom adapters. Contact us for Enterprise integration support.

How does protocol detection work?

The Protocol Detector middleware inspects request headers, signatures and body shape to identify the protocol. Each match carries a confidence value; an explicit `X-Protocol` header gives 1.0, and header- or signature-shape inference gives less. Below the detector's threshold no protocol is assumed and the request is handled as plain REST. No manual configuration is needed on the agent side.

See how agents connect Read the developer docs